Clock gene expression in mouse kidney and testis: analysis of periodical and dynamical patterns.

Molecular clocks drive circadian rhythmicity of cellular functions in peripheral tissues and organs, kidney included, whereas in the testis this clockwork seems constitutively active. We have evaluated the periodicity and the dynamics of expression of the clock genes BMAL1, CLOCK, PER1, PER2, CRY1, CRY2 and REV ERBalpha over 24 h in the kidney and testis using a mouse model. The periodicity was explored by single cosinor, and dynamics were explored by calculation of fractional variations of gene expression related to time intervals. Kidney and testis were harvested at 4-h intervals over a 24-h period from eight-week-old C57BL/6 male mice housed individually on a 12 h light (L)-dark (D) cycle (lights on at 08:00 h; lights off at 20:00 h) and mRNA was extracted and analyzed by Quantitative Real-time Reverse Transcription PCR. A statistically significant difference was evidenced between kidney and testis for the original values of expression level of BMAL1, PER1, PER2 CRY1, CRY2 and REV ERBα. A statistically significant difference was evidenced between kidney and testis for the fractional variation of BMAL1, PER2, CRY1, CRY2 and REV ERBα. A significant 24-h rhythmic component was found for BMAL1, CLOCK, PER1, PER2, CRY1, CRY2 and REV ERBα in the kidney, whereas no core clock gene showed circadian rhythmicity in the testis. Fractional variations provided significant circadian rhythms for BMAL1, PER2, CRY, CRY2 and REV ERBα in the kidney, whereas in the testis the fractional variation calculations showed no circadian rhythmicity, but quantitative comparison showed statistically significant differences in only 16.7 percent of the time points studied. In conclusion, in the kidney the clock gene machinery shows circadian oscillation of mRNA levels and time-related variations in the rate of change of clock gene expression. In the testis the clock genes do not show circadian rhythmicity of expression and the dynamics of variation are not characterized by a periodical pattern, but are quantitatively similar to those observed in the kidney. These data suggest that in the testis the clock gene machinery shows a tissue-specific pattern of function and clock genes may play a different role in the testis with regard to other peripheral tissues, maybe in relation to the presence of developmental and differentiation phenomena.

[1]  Paolo Sassone-Corsi,et al.  A Web of Circadian Pacemakers , 2002, Cell.

[2]  E. Bittman,et al.  Period gene expression in mouse endocrine tissues. , 2003, American journal of physiology. Regulatory, integrative and comparative physiology.

[3]  H. Okamura.  Clock Genes in Cell Clocks: Roles, Actions, and Mysteries , 2004, Journal of biological rhythms.

[4]  V. King,et al.  Persistent twenty-four hour changes in liver and bone marrow despite suprachiasmatic nuclei ablation in mice. , 2004, American journal of physiology. Regulatory, integrative and comparative physiology.

[5]  P. Sassone-Corsi,et al.  On the communication pathways between the central pacemaker and peripheral oscillators. , 2003, Novartis Foundation symposium.

[6]  M. D'Esposito,et al.  Molecular cloning and characterization of the clock gene period2 in the testis of lizard Podarcis sicula and its expression during seasonal reproductive cycle. , 2005, Gene.

[7]  P. Sassone-Corsi,et al.  No circadian rhythms in testis: Period1 expression is clock independent and developmentally regulated in the mouse. , 2003, Molecular endocrinology.

[8]  E. Borrelli,et al.  Regulation of BMAL1 Protein Stability and Circadian Function by GSK3β-Mediated Phosphorylation , 2010, PloS one.

[9]  Steve A. Kay,et al.  Redundant Function of REV-ERBα and β and Non-Essential Role for Bmal1 Cycling in Transcriptional Regulation of Intracellular Circadian Rhythms , 2008, PLoS genetics.

[10]  A. B. Reddy,et al.  A clockwork web: circadian timing in brain and periphery, in health and disease , 2003, Nature Reviews Neuroscience.

[11]  Erin L. McDearmon,et al.  The genetics of mammalian circadian order and disorder: implications for physiology and disease , 2008, Nature Reviews Genetics.

[12]  P. Chan,et al.  Chronobiological Analysis of Circadian Patterns in Transcription of Seven Key Clock Genes in Six Peripheral Tissues in Mice , 2007, Chronobiology international.

[13]  M. Lehman,et al.  Expression of haPer1 and haBmal1 in Syrian Hamsters: Heterogeneity of Transcripts and Oscillations in the Periphery , 2004, Journal of biological rhythms.

[14]  Masamitsu Iino,et al.  System-level identification of transcriptional circuits underlying mammalian circadian clocks , 2005, Nature Genetics.

[15]  A. Sehgal,et al.  The Thymus Is Similar to the Testis in Its Pattern of Circadian Clock Gene Expression , 2005, Journal of biological rhythms.

[16]  A. Sehgal,et al.  Non-cyclic and Developmental Stage-Specific Expression of Circadian Clock Proteins During Murine Spermatogenesis1 , 2003, Biology of reproduction.

[17]  Steven M. Reppert,et al.  Posttranslational Mechanisms Regulate the Mammalian Circadian Clock , 2001, Cell.

[18]  Ryusuke Okura,et al.  Circadian clock genes directly regulate expression of the Na(+)/H(+) exchanger NHE3 in the kidney. , 2005, Kidney international.

[19]  S. Reppert,et al.  Molecular analysis of mammalian circadian rhythms. , 2001, Annual review of physiology.

[20]  Haruhiko Soma,et al.  Transcriptional oscillation of canonical clock genes in mouse peripheral tissues , 2004, BMC Molecular Biology.

[21]  S. Kay,et al.  Time zones: a comparative genetics of circadian clocks , 2001, Nature Reviews Genetics.

[22]  E. Eide,et al.  The Circadian Regulatory Proteins BMAL1 and Cryptochromes Are Substrates of Casein Kinase Iε* , 2002, The Journal of Biological Chemistry.

[23]  Felix Naef,et al.  Circadian Gene Expression in Individual Fibroblasts Cell-Autonomous and Self-Sustained Oscillators Pass Time to Daughter Cells , 2004, Cell.

[24]  L. Stow,et al.  Regulation of αENaC expression by the circadian clock protein Period 1 in mpkCCD(c14) cells. , 2010, Biochimica et biophysica acta.

[25]  A. Sehgal,et al.  The Circadian Clock Protein BMAL1 Is Necessary for Fertility and Proper Testosterone Production in Mice , 2008, Journal of biological rhythms.

[26]  B. Gvakharia,et al.  Temporal and Spatial Expression of the period Gene in the Reproductive System of the Codling Moth , 2000, Journal of biological rhythms.

[27]  Masaaki Ikeda,et al.  Interactivating feedback loops within the mammalian clock: BMAL1 is negatively autoregulated and upregulated by CRY1, CRY2, and PER2. , 2002, Biochemical and biophysical research communications.

[28]  P. Bebas,et al.  Circadian clock and output genes are rhythmically expressed in extratesticular ducts and accessory organs of mice , 2009, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[29]  G. Mazzoccoli.  The timing clockwork of life. , 2011, Journal of Biological Regulators and Homeostatic Agents.

[30]  S. Carlson,et al.  Circadian rhythm of plasma sodium is disrupted in spontaneously hypertensive rats fed a high-NaCl diet. , 2000, American journal of physiology. Regulatory, integrative and comparative physiology.

[31]  Ueli Schibler,et al.  The Orphan Nuclear Receptor REV-ERBα Controls Circadian Transcription within the Positive Limb of the Mammalian Circadian Oscillator , 2002, Cell.